1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*/
#include "tomcrypt.h"
/**
@file ctr_encrypt.c
CTR implementation, encrypt data, Tom St Denis
*/
#ifdef LTC_CTR_MODE
/**
CTR encrypt software implementation
@param pt Plaintext
@param ct [out] Ciphertext
@param len Length of plaintext (octets)
@param ctr CTR state
@return CRYPT_OK if successful
*/
static int _ctr_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CTR *ctr)
{
int x, err;
while (len) {
/* is the pad empty? */
if (ctr->padlen == ctr->blocklen) {
/* increment counter */
if (ctr->mode == CTR_COUNTER_LITTLE_ENDIAN) {
/* little-endian */
for (x = 0; x < ctr->ctrlen; x++) {
ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
if (ctr->ctr[x] != (unsigned char)0) {
break;
}
}
} else {
/* big-endian */
for (x = ctr->blocklen-1; x >= ctr->ctrlen; x--) {
ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
if (ctr->ctr[x] != (unsigned char)0) {
break;
}
}
}
/* encrypt it */
if ((err = cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key)) != CRYPT_OK) {
return err;
}
ctr->padlen = 0;
}
#ifdef LTC_FAST
if ((ctr->padlen == 0) && (len >= (unsigned long)ctr->blocklen)) {
for (x = 0; x < ctr->blocklen; x += sizeof(LTC_FAST_TYPE)) {
*(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ct + x)) = *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)pt + x)) ^
*(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ctr->pad + x));
}
pt += ctr->blocklen;
ct += ctr->blocklen;
len -= ctr->blocklen;
ctr->padlen = ctr->blocklen;
continue;
}
#endif
*ct++ = *pt++ ^ ctr->pad[ctr->padlen++];
--len;
}
return CRYPT_OK;
}
/**
CTR encrypt
@param pt Plaintext
@param ct [out] Ciphertext
@param len Length of plaintext (octets)
@param ctr CTR state
@return CRYPT_OK if successful
*/
int ctr_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CTR *ctr)
{
int err, fr;
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(ctr != NULL);
if ((err = cipher_is_valid(ctr->cipher)) != CRYPT_OK) {
return err;
}
/* is blocklen/padlen valid? */
if ((ctr->blocklen < 1) || (ctr->blocklen > (int)sizeof(ctr->ctr)) ||
(ctr->padlen < 0) || (ctr->padlen > (int)sizeof(ctr->pad))) {
return CRYPT_INVALID_ARG;
}
#ifdef LTC_FAST
if (ctr->blocklen % sizeof(LTC_FAST_TYPE)) {
return CRYPT_INVALID_ARG;
}
#endif
/* handle acceleration only if pad is empty, accelerator is present and length is >= a block size */
if ((cipher_descriptor[ctr->cipher].accel_ctr_encrypt != NULL) && (len >= (unsigned long)ctr->blocklen)) {
if (ctr->padlen < ctr->blocklen) {
fr = ctr->blocklen - ctr->padlen;
if ((err = _ctr_encrypt(pt, ct, fr, ctr)) != CRYPT_OK) {
return err;
}
pt += fr;
ct += fr;
len -= fr;
}
if (len >= (unsigned long)ctr->blocklen) {
if ((err = cipher_descriptor[ctr->cipher].accel_ctr_encrypt(pt, ct, len/ctr->blocklen, ctr->ctr, ctr->mode, &ctr->key)) != CRYPT_OK) {
return err;
}
pt += (len / ctr->blocklen) * ctr->blocklen;
ct += (len / ctr->blocklen) * ctr->blocklen;
len %= ctr->blocklen;
}
}
return _ctr_encrypt(pt, ct, len, ctr);
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
|
